BACKGROUND: CRC is the third leading cause of cancer-related deaths in the United States. Colonoscopy, an invasive test that allows for direct visualization of the colon, is the most common test used to screen for CRC. Non-adherence to colonoscopy (estimated to be 25% to 45%) represents a significant problem and contributes to CRC-related morbidity and mortality. A multi-component intervention using peer coaches has the potential to improve adherence since it allows for individualized tailored support and can be used to modify multiple factors that are necessary for behavior change (increased adherence). METHODS: Dr. Sultan and her mentoring team will develop a multi-component peer coach intervention (MCPCI), based on the theoretical framework of the Integrative Model of Behavior Prediction, to increase colonoscopy adherence rates among veterans. Using qualitative research techniques, focus groups will be conducted to determine the factors that veterans perceive as barriers and facilitators for colonoscopy completion (Aim 1a). Findings from this study will be directly used to develop a Peer Coach Toolkit, which will be a manual to be used by peer coaches as part of the MCPCI. This Toolkit will contain educational materials, texted scripts for motivating veterans to be adherent, and strategies to overcome the most commonly identified barriers to colonoscopy completion. This Toolkit will be field-tested and refined using focus groups of veterans and providers (Aim 1b). Aim 2 consists of recruiting, training, and developing a formal peer coach training program, which will include motivational interviewing techniques. Aim 3 will consist of conducting two separate pilot studies. Pilot study #1 will identify characteristics associated with adherence to colonoscopy for development of a prototype predictive model. Using a random convenience sample of 218 veterans referred for screening and diagnostic colonoscopy, information regarding clinical, demographic, and psychosocial characteristics will be obtained using telephone interviews and electronic medical chart review. The primary outcome will be adherence to colonoscopy. Multivariate logistic regression will be used to develop a prototype predictive model. Pilot study #2 will test the feasibility of telephone- based peer coach interviews using the MCPCI in a random convenience sample of 215 veterans referred for screening and diagnostic colonoscopy. Veterans, who are likely to be non- adherent using the prototype predictive model, will be assigned a peer coach. Peer coaches will use the Peer Coach Toolkit to deliver the MCPCI via the telephone. Primary outcome will process outcomes related to feasibility of telephone interviews. For Aim 4 we will conduct a formative evaluation to optimize the MCPCI prior to formal testing. SIGNIFICANCE: The incidence of CRC in veterans is currently estimated to be 4,000 cases annually. Programs that successfully improve adherence to colonoscopy completion are critical for reducing CRC-related morbidity and mortality among veterans.